Activation by levcromakalim and metabolic inhibition of glibenclamide-sensitive K channels in smooth muscle cells of pig proximal urethra
Version of Record online: 19 JUL 2012
1996 British Pharmacological Society
British Journal of Pharmacology
Volume 118, Issue 3, pages 635–642, June 1996
How to Cite
Teramoto, N. and Brading, A. F. (1996), Activation by levcromakalim and metabolic inhibition of glibenclamide-sensitive K channels in smooth muscle cells of pig proximal urethra. British Journal of Pharmacology, 118: 635–642. doi: 10.1111/j.1476-5381.1996.tb15448.x
- Issue online: 19 JUL 2012
- Version of Record online: 19 JUL 2012
- Received September 7, 1995; Revised February 19, 1996; Accepted February 21, 1996
- potassium channels;
- potassium channel opener;
- resting membrane potential;
- urethral resting tone
- 1The effects of levcromakalim (BRL 38227) on ionic currents recorded from pig proximal urethra were investigated by use of tension measurement and patch clamp techniques (conventional whole-cell configuration, nystatin perforated patch, and cell-attached configuration).
- 2Levcromakalim (1 μm) caused a relaxation in the resting tone. This levcromakalim-induced relaxation was inhibited by the pretreatment with 1 μm glibenclamide.
- 3The resting membrane potential recorded from single cells in current-clamp mode was −36.1 ± 4.4 mV (n = 5).
- 4Levcromakalim induced a concentration-dependent hyperpolarization with a maximum (at ≥ 10 μm) close to the theoretical equilibrium potential of potassium (EK). The membrane hyperpolarization caused by 1 μm levcromakalim (24.7 ± 5.8 mV, n = 4) was abolished by 1 μm glibenclamide.
- 5Levcromakalim (100 μm) caused an outward K current in whole-cell recordings which was unaffected by iberiotoxin (300 nM) but abolished by glibenclamide (10 μm).
- 6In cell-attached patches, levcromakalim activated a 43 pS K channel which was inhibited by the application of glibenclamide.
- 7The metabolic poison, cyanide (CN), also activated a 43 pS K channel which was suppressed by the application of 10 μm glibenclamide.
- 8These results indicate that levcromakalim and metabolic inhibition activate the same 43 pS K channel in pig proximal urethra. The resultant urethral hyperpolarization might reduce the usefulness of K channel openers in the treatment of detrusor instability, but be of value in treating outflow obstruction.